I ordered this to bring my best buddy/gallery director, @JustMerle with me on short walks and picnics in the small town we are in. It arrived quickly, is lightweight and folds really small and flat which is great for storage. It opens easily and is roomy enough for my chonky kitty who is probably around 12-15#. The back extension is roomy and not angled like many others. He walked right in and checked it out. The zippered areas are secure and the main one has a feature to keep him from opening the zippers. The side pockets are spacious and hold a phone, beverage, keys, money etc. There is a good mix of windows and screen areas so even on a hot day it should have plenty of ventilation.Many others I have seen have large clear window areas but not much screen areas and they often come with fans so I assume they can get pretty hot. He could stand up and lay down with plenty of room with the back extension closed. Many others available are smaller so check dimensions when shopping. I put this on in the front when I walked so I could monitor him better. It was comfortable and the straps adjusted to secure it to lessen bounce while walking. He did really well, I opened the extension when we got to the top of the hill and it was nice to have my friend with me while watching the sunset! He was calm and didn't seem like he felt trapped; he was just curious about what was around and all the sounds, birds etc. I expect on future trips he will settle and lay down or even nap.I am very happy with this product, the design, features, and quality. It has the best of just about all the various backpacks out there, all in one.Lots of people seem hesitant to get a soft sided backpack vs the spaceship type hard body versions available, but when I saw the reviews for this were just as good I ordered it and am so glad I did. You will not be disappointed if you order this! As a bonus, this can also be used for trips to the vet. They seem to prefer soft carriers rather than hard sided carriers and with this there are multiple access doors so the vet does not have to reach in for a scared cat. I will probably leave this out for him all the time to have a little hideaway of his own also.